Flexible junction for submarine cables



y 0, 1950 G. POUZ T 2,509,524

FLEXIBLE JUNCTION FOR SUBMARINE CABLES Filed Oct. 16, 1947 I IV VE/Y 70RGEORGES P0 UZET HTTO/PNEYS' Patented May 30, 1950 FLEXIBLE JUNCTION FORSUBMARINE CABLES Georges Pouzet, Paris, France, assignor to CompagnieGeneral DElectricite, Paris, France, a

corporation of France Application October 16, 1947, Serial No. 780,277In France October 16, 1946 4 Claims. 1

The present invention is concerned with flexible housings or junctionboxes for use on submarine cables, to resist pressure at great depthsand to contain the mechanical or electrical appliances, in particularthe amplifiers or repeaters required for the operating of submarinecables.

The application of Paul Martin for I1nprove ments to mechanicalapparatus functioning under pressure, particularly submarine'telephonicrepeaters, Ser. No. 624,271, filed October 24, 1945, demonstrates theprinciple of such a junction box by means of a flexible casingcontaining an incompressible insulating liquid, capable ofbalancingitself, under pressures, with the depth pressure, in which are mountedthe appliances constituting the electrical equipment, either directly orin watertight casings resistant to. depth pressures.

The present invention relates to a special design of a flexible junctionbox for a submarine cable, on the basis of the mentioned principle.

According to this principle, the flexible body of the junction box,containing the pressure equalising liquid, should fulfil the followingconditions:

It should be tight against seawater and be impervious tov its action;

It should be sufficiently pliable to ensure that no appreciabledifference in pressure between the interior and the exterior of thejunction box can set in, particularly, at low pressures while immersing;

It should be sufficiently flexible to wind over the cable-layingmachines;

It should not collapse under the force of laying strains while travelingover the capstan of the cable ship or over the pulleys or drums fixed atfront or rear of the cable ship, at the time of laying;

It should ensure electrical. continuity not only of the centralconductor, but also of the concentric conductor of the cable.

To satisfy these different conditions, the flexible body of therjunctionbox is constituted by a copper cylindrical tube having fluted surfaces,the flutings supported on. pressure-resistant steel rings resting on asupporting bearing, an arrange-.- ment embodying certain effectivefeatures for the advantageousemployment of such a junction box adapted,as it is, for internal. fillingwith a pressure-balancing liquid.Thesefeatures, which are 2v the object of this present invention, areexplained in the following description:

In the application of this junction box here described, the thickness ofthe pressure-resistant rings can be reduced, theirpurposebeing simply toprevent the flexible body from collapsing when being passed over thecable-laying machinery, under the forceof the strain during laying.

To increase the flexibility of, the cylindrical body, it is proposed toincreaselthe depth of the surface fiutings and to reducethe thickness ofthis surface wall.

Following the lines of the present invention, it isalso proposed tosubmit the cylindrical junction body filled with insulating liquid to aninitial internal pressure higher than the atmospheric pressure, thevolume of the pressure chosen. being equal to, or preferably higher thanthat necessary to deform from outside the flexible body ofithe junctionbox. Thus, during immersion. of the apparatus, the watertight fittingsat the endsof the flexible body will be submitted to' a. pressure,coming from the interior of the box, .hi'gher than the external pressureresulting from thedepth of the water, up to the moment when thewaterpressure is great enough to deformthefl'exi'blc body of the junction boxand: equalise the pressures between the interior and the exterior'of:the junction box, thus preventing any penetration by water through the.watertight. joints: Another effect of this initial pressureapplication", which deforms the flutings towards the exterior, is toensure absolutely the pressure regulation of the box under the appliedforceof depth pressure; for the interior deformationrof theinteriorsurface towards the exterior affordsthelatter a certain play in relationto the supporting bear ings, and facilitates deformation in the inversesense, towards the-interior under! the actionof the pressure at thedepth.

The diagrams shown on the attached drawing show the object of the:present invention, and some modified forms.

Fig. 1 showsin: sectiona portion of the hollow cylindrical body of thejunction box and one arrangement for the end of thejunction body,embodying the terminal piece for cable entry and the members forensuring:impermeability and for filling the junction bodywith-theinsulating liquid.

Fig, 2 shows the extremity 'of 'the'flexib'ledun'ction piece, withprogressive passage from the diameter of the cable to the diameter ofthe junction box.

In these diagrams, I shows one of the essential electrical parts as arepeater mounted in the flexible junction box and attached to the twosubmarine cables; 2 shows one of the submarine cables. The flexiblecylindrical junction body 3 preferably constituted by a coppercylindrical tube having fluted or'undulated peripheral surfaces, issupported by steel rings 4 and 5 through the intermediary of asupporting member 6.

According to a preferred form of the present invention, the steel rings4 and 5 fit into one another along surfaces of spherical contact, butthey may be of another form without going beyond the scope of thepresent invention.

The supporting member 6 may be made up of successive rings if theflutings or undulations of the wall of cylindrical junction body 3 areparallel, or on the contrary they can take the form of a spiral coil ifthe flutings of junction body 3 are themselves of spiral form, in factthe supporting member 6 can be of circular section or otherwise; it maybe metallic or not, solid or hollow, according to the degree of flexibledeformability which it is desired to confer on the surface of theflexible box 3 when under depth pressure, in order to bring aboutperfect pressure equilibrium between the interior and the exterior ofthe junction box or body.

The mechanical connection of the junction body 3 with the end piece I,which is of bronze or copper, as well as tight packing between these twoparts, is assured by the combined action of the screwed pieces 8 and 9,also of copper, and of the inset packing joint It. Of course, tightnessbetween tube 3 and end piece I can be achieved in any other manner, andin particular by soldering.

The end-piece I is traversed by the cable 2 stripped of its covering asfar as the insulation. Tightness between this end piece I and the cable2 is ensured by ringed packing joints II compressed by the metal capclamping device I2.

The metal end piece l has an axial bore extending part of the waytherethrough, in the bottom of which bore the packing II is positioned.A shoulder on clamping device I2 extends part way into the axial bore ofend piece I, which shoulder threadedly engages the wall of the axialbore of end piece 7. These packing joints II are made of impermeablematerial easily deformed, resistant to seawater action and to thepressure equalising liquid inside the junction body. Their design issuch as to render them self-packing under the action of pressure appliedeither from the interior or from the exterior of the junction box.

The cable passes through a traverse cableentry terminal made ofinsulating protective metal I3 of high mechanical resistance and havinga protective metal mechanical guard I4 molded in with it whose flange isfixed to the end piece 'I. The cable conductor I5 is fixed against thecable-entry guard by the nut I6 screwed on to the threaded end of theconductor, and is connected to the electrical repeating apparatus I.

A little play is left between the flange of the cable-entry guard I sand the part I to enable the pressure equalising liquid to act on thejoint I I and on the length of cable in the terminal.

Further, the end piece I has openings to allow application of a vacuumand application of pressure to the flexible junction body 3 by means of4 the pressure equalising liquid. These openings are closed byscrew-plugs I1 and I8 or by any other suitable device.

The outer concentric conductor I9 of the cable is mechanically fixed toclamping piece I2 and electrically connected to end piece '17 by aflexible piece (not shown) passing across clamping piece I2 and solderedat the extremities to the appropriate connections. The end piece I is inturn connected to the ground terminal of the electrical apparatus I by aflexible connection (not shown) soldered at the ends to the appropriateconnections. In this way the electrical continuity of the concentricconductor is perfectly ensured through soldered contacts.

Adjustment between the extremities of the cylindrical body of thejunction box and the cables is effected by means of a flexible member ofconical frustrum type 2t. It may be constructed, in particular, as shownin Figs. 1 and 2, by a copper spiral coil, in one or more elements, oneend of which is screwed on to the clamping piece I2 and the other endsecured on the cable 2, e. g., as shown in Fig. 2 by the assemblage ofbushes 2I of conical exterior form as outlined by the piece 22 screwingOn to the piece 23 which itself screws on to the extremity of the spiralcoil 2i). Care is observed in fixing to allow the cable a certainslackness between its entry into the end piece 1 and the extremity ofthe coil 2%, to enable the cable to deform when being laid, withoutexercising any drag on the cable at the entrance to end piece l.

After fitting the junction box to the two cables to be connected, thejunction box is provided with a resilient jacketof textile, rubber orother material-then covered with an armor which will be connected to thecables on both sides of the junction box.

It will be apparent to those skilled in the art that my invention issusceptible of modifications to adapt the same to particular conditions,and all such modifications which are within the scope of the appendedclaims I consider to be comprehended with the spirit of my invention.

Having now particularly described and ascertained the nature of saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. In a junction box housing for submarine cables, a flexible, metallic,cylindrical tubular casing, interlocking sets of metal rings forming asubstantially continuous cylindrical surface, adapted to fit within saidcasing adjoining the radially innermost points of the flutings thereof,deformable support means mounted within the inner faces of said flutingsbetween said casing and said rings and adapted to deformably supportsaid casing on said rings, a metal end piece having a cylindricalportion fitting within one end of said casing, means comprising metalpacking rings carried by said end piece for tightly holding the end ofsaid casing against said cylindrical portion of said end piece, said endpiece being provided with an axial aperture adapted to receive a cableend, a metal cap member tight- 1y secured to said end piece and havingan axial aperture for the passage of a cable end therethrough, packingmeans retained by said cap member against said cable end and theaperture in said end piece through which said cable end passes, aninsulating terminal member surrounding the portion of said cable endprojecting inside said casing beyond said end piece, and a metal guardsurrounding said terminal member and fixed to the inner face of said endpiece, said end piece being provided with valve controlled channel inletmeans for introducing liquid under pressure within said casing.

2. A housing according to claim 1, the face of said end piece adjacentsaid guard being slightly recessed adjacent said cable end for receivingtherein pressure fluid from the interior of said casing.

3. A housing according to claim 1, said end piece being provided with anaxial bore extending for a fraction of its thickness from its end remotefrom the interior of said casing, said packing means being positioned inthe bottom of said bore surrounding said cable, and said cap memberhaving a threaded stud portion which threadedly engages the interior ofsaid bore and holds said packing means tightly in said bore.

4. A housing according to claim 1, and said cap member being providedexteriorly with a helical groove, and a conical helical metal coilhaving at one of its ends, turns received within said groove, andbushing means carried on said cable end at a point spaced from saidhousing and provided with an internal groove wherein are received turnsof the other end of said coil.

GEORGES POUZET.

REFERENCES CITED Name Date Wentz Mar. 8, 1938 Number

